Lattice QCD static potentials of the meson-meson and tetraquark systems computed with both quenched and full QCD (original) (raw)
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Detailed analysis of the tetraquark potential and flip-flop in SU(3) lattice QCD
Physical Review D, 2005
We perform the detailed study of the tetraquark (4Q) potential V4Q for various QQ-QQ systems in SU(3) lattice QCD with β = 6.0 and 16 3 × 32 at the quenched level. For about 200 different patterns of 4Q systems, V4Q is extracted from the 4Q Wilson loop in 300 gauge configurations, with the smearing method to enhance the ground-state component. We calculate V4Q for planar, twisted, asymmetric, and large-size 4Q configurations, respectively. Here, the calculation for large-size 4Q configurations is done by identifying 16 2 × 32 as the spatial size and 16 as the temporal one, and the long-distance confinement force is particularly analyzed in terms of the flux-tube picture. When QQ andQQ are well separated, V4Q is found to be expressed as the sum of the one-gluon-exchange Coulomb term and multi-Y type linear term based on the flux-tube picture. When the nearest quark and antiquark pair is spatially close, the system is described as a "two-meson" state. We observe a flux-tube recombination called as "flip-flop" between the connected 4Q state and the "two-meson" state around the level-crossing point. This leads to infrared screening of the long-range color forces between (anti)quarks belonging to different mesons, and results in the absence of the color van der Waals force between two mesons.
Study of the gluon-quark-antiquark static potential in SU(3) lattice QCD
Physical Review D, 2008
We study the long distance interaction for hybrid hadrons, with a static gluon, a quark and an antiquark with lattice QCD techniques. A Wilson loop adequate to the static hybrid three-body system is developed and, using a 24^3 x 48 periodic lattice with beta=6.2 and a ~ 0.075 fm, two different geometries for the gluon-quark segment and the gluon-antiquark segment are investigated. When these segments are perpendicular, the static potential is compatible with confinement realized with a pair of fundamental strings, one linking the gluon to the quark and another linking the same gluon to the antiquark. When the segments are parallel and superposed, the total string tension is larger and agrees with the Casimir Scaling measured by Bali. This can be interpreted with a type-II superconductor analogy for the confinement in QCD, with repulsion of the fundamental strings and with the string tension of the first topological excitation of the string (the adjoint string) larger than the double of the fundamental string tension.
Static three quark potential in the quenched lattice QCD
Nuclear Physics B - Proceedings Supplements, 2001
We study the static three quark potential using lattice QCD simulation. At zero temperature, the three quark potential is extracted from the baryonic Wilson loop and fitted to the phenomenological form, the sum of the Coulomb term, linearly rising term and the constant. We compare two types of the linear term, "Y " and "∆" type, and find that the string tension almost coincide with σ QQ in the former case. We also investigate the three quark potential at finite temperature using the Polyakov loop correlation. In the deconfined phase, the screened potential is observed similarly to the case of QQ system.
SU(3) lattice QCD study for static three-quark potential
AIP Conference Proceedings
We study the static three-quark (3Q) potential in detail using SU(3) lattice QCD with 12 3 × 24 at β = 5.7 and 16 3 × 32 at β = 5.8, 6.0 at the quenched level. For more than 200 patterns of the 3Q systems, we numerically derive 3Q ground-state potential V 3Q from the 3Q Wilson loop with the smearing technique, which reduces excited-state contaminations. The lattice QCD data of V 3Q are well reproduced within a few % deviation by a sum of a constant, the two-body Coulomb term and the three-body linear confinement term σ 3Q L min , with L min the minimal value of total length of color flux tubes linking the three quarks. From the comparison with the Q-Q potential, we find a universality of the string tension as σ 3Q σ QQ and the one-gluon-exchange result for Coulomb coefficients, A 3Q 1 2 A QQ .
Static Potential for the Quark-Antiquark-Gluon Hybrid System In Lattice QCD
Arxiv preprint arXiv:0710.1762, 2007
The static gluon-quark-antiquark interaction is investigated using lattice QCD techniques. A Wilson loop adequate to the static hybrid three-body system is developed and, using a 24 3 × 48 periodic lattice with β = 6.2, the potential energy of the system is measured for different geometries. For the medium range behaviour, when the quarks are far apart, we find a string tension which is compatible with two fundamental strings. On the other hand, when the quark and antiquark are nearby, the string tension is larger than two fundamental strings and is compatible with the Casimir scaling.
Tetraquark and Pentaquark Systems in Lattice QCD
Journal of Modern Physics, 2016
Motivated by the recent experimental discoveries of multi-quark candidates, e.g., the Θ + (1540), we study multi-quark systems in lattice QCD. First, we perform accurate mass measurements of low-lying 5Q states with J = 1/2 and I = 0 in both positive-and negative-parity channels in anisotropic lattice QCD. The lowest positive-parity 5Q state is found to have a large mass of about 2.24GeV after the chiral extrapolation. To single out the compact 5Q state from N K scattering states, we develop a new method with the hybrid-boundary condition (HBC), and find no evidence of the compact 5Q state below 1.75GeV in the negativeparity channel. Second, we perform the first study of the multi-quark potential in lattice QCD to clarify the inter-quark interaction in multi-quark systems. The 5Q potential V 5Q for the QQ-Q-QQ system is found to be well described by the "OGE Coulomb plus multi-Y Ansatz": the sum of the one-gluon-exchange (OGE) Coulomb term and the multi-Y-type linear term based on the flux-tube picture. The 4Q potential V 4Q for the QQ-QQ system is also described by the OGE Coulomb plus multi-Y Ansatz, when QQ andQQ are well separated. The 4Q system is described as a "two-meson" state with disconnected flux tubes, when the nearest quark and antiquark pair is spatially close. We observe a lattice-QCD evidence for the "flip-flop", i.e., the flux-tube recombination between the connected 4Q state and the "two-meson" state. On the confinement mechanism, the lattice QCD results indicate the flux-tube-type linear confinement in multi-quark hadrons. * Talk presented by Fumiko Okiharu at "Quark Nuclear Physics 2005" (QNP05).
Dynamical effects of QCD in q2q̄2 systems
2016
We study the coupling of a tetraquark system to an exchanged meson-meson channel, using a pure gluonic theory based four-quark potential matrix model which is known to fit well a large number of data points for lattice simulations of different geometries of a four-quark system. We find that if this minimal-area-based potential matrix replaces the earlier used simple Gaussian form for the gluon field overlap factor f in its off-diagonal terms, the resulting T-matrix and phase shifts develop an angle dependence whose partial wave analysis reveals D wave and higher angular momentum components in it. In addition to the obvious implications of this result for the meson-meson scattering, this new feature indicates the possibility of orbital excitations influencing properties of meson-meson molecules through a polarization potential. We have used a formalism of the resonating group method, treated kinetic energy and overlap matrices on model of the potential matrix, but decoupled the resulting complicated integral equations through the Born approximation. In this exploratory study we have used a quadratic confinement and not included the spin-dependence; we also used the approximation of equal constituent quark masses.
Physical Review D, 2010
The chromoelectric and chromomagnetic elds, created by a static gluon-quark-antiquark system, are computed in quenched SU(3) lattice QCD, in a 24 3 × 48 lattice at β = 6.2 and a = 0.07261(85) f m. We compute the hybrid Wilson Loop with two spatial geometries, one with a U shape and another with an L shape. The particular cases of the two gluon glueball and quarkantiquark are also studied, and the Casimir scaling is investigated in a microscopic perspective. This microscopic study of the colour elds is relevant to understand the structure of hadrons, in particular of the hybrid excitation of mesons. This also contributes to understand connement with ux tubes and to discriminate between the models of fundamental versus adjoint conning strings, analogous to type-II and type-I superconductivity. I.
Detailed analysis of the three-quark potential in SU(3) lattice QCD
Physical Review D, 2002
The static three-quark (3Q) potential is studied in detail using SU(3) lattice QCD with 12 3 × 24 at β = 5.7 and 16 3 × 32 at β = 5.8, 6.0 at the quenched level. For more than 300 different patterns of the 3Q systems, we perform the accurate measurement of the 3Q Wilson loop with the smearing method, which reduces excited-state contaminations, and present the lattice QCD data of the 3Q ground-state potential V3Q. We perform the detailed fit analysis on V3Q in terms of the Y-ansatz both with the continuum Coulomb potential and with the lattice Coulomb potential, and find that the lattice QCD data of the 3Q potential V3Q are well reproduced within a few % deviation by the sum of a constant, the two-body Coulomb term and the three-body linear confinement term σ3QLmin, with Lmin the minimal value of the total length of color flux tubes linking the three quarks. From the comparison with the Q-Q potential, we find a universality of the string tension as σ3Q ≃ σ QQ and the one-gluon-exchange result for the Coulomb coefficients as A3Q ≃ 1 2 A QQ . We investigate also the several fit analyses with the various ansätze: the Y-ansatz with the Yukawa potential, the ∆-ansatz and a more general ansatz including the Y and the ∆ ansätze in some limits. All these fit analyses support the Y-ansatz on the confinement part in the 3Q potential V3Q, although V3Q seems to be approximated by the ∆-ansatz with σ∆ ≃ 0.53σ.
Exotic mesons in quenched lattice QCD
Physical Review D, 1997
Since gluons in QCD are interacting fundamental constituents just as quarks are, we expect that in addition to mesons made from a quark and an antiquark, there should also be glueballs and hybrids (bound states of quarks, antiquarks and gluons). In general, these states would mix strongly with the conventional q-bar-q mesons. However, they can also have exotic quantum numbers inaccessible to q-bar-q mesons. Confirmation of such states would give information on the role of "dynamical" color in low energy QCD. In the quenched approximation we present a lattice calculation of the masses of mesons with exotic quantum numbers. These hybrid mesons can mix with four quark (q-bar-q-bar-q-q) states. The quenched approximation partially suppresses this mixing. Nonetheless, our hybrid interpolating fields also couple to four quark states. Using a four quark source operator, we demonstrate this mixing for the 1-+ meson. Using the conventional Wilson quark action, we calculate both at reasonably light quark masses, intending to extrapolate to small quark mass, and near the charmed quark mass, where we calculate the masses of some c-bar-c-g hybrid mesons. The hybrid meson masses are large --- over 4 GeV for charmonium and more than twice the vector meson mass at our smallest quark mass, which is near the strange quark mass.